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Analysis Of Fluid-induced Vibration Characteristics Of Centrifugal Compressor

Posted on:2020-12-21Degree:MasterType:Thesis
Country:ChinaCandidate:Z P MenFull Text:PDF
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With the development of technology and industry,centrifugal compressors are more widely used and have higher performance requirements.How to improve its stable operation has gradually become the main content of research in this field.Since the bearings used in today's centrifugal compressors are mainly sliding bearings,the stability of the oil film support inside the sliding bearings,and the fluid excitation force inside the centrifugal compressor have gradually become the main aspects that affect the further improvement of centrifugal compressors' performance.The object studied in this paper is the tilting pad bearing in sliding bearings,and the research content is the analysis of the running stability of a rotor which is supported by a five-watt tilting pad bearing and is subjected to the action of the fluid excitation force during operation,including the internal hydrodynamic characteristics of tilting pad bearings,the impeller clearance excitation force and the influence of the impeller clearance fluid force on the rotor system under the support of the tilting pad film,and the purpose of this paper is to provide theoretical guidance for the design of centrifugal compressor in the future by using the response analysis and calculation of the rotor under the impact of the proportional model.Firstly,the fluid film properties and various boundary conditions are analyzed by means of hydrodynamics.Through the calculation of the lubrication equation of the bearing,the stiffness and damping of the sliding bearing can be calculated in the future.In addition,the phenomenon of oil film instability under the support of the sliding bearing rotor and the influence of oil film instability on the rotating subsystem are analyzed and explained.Secondly,the impeller clearance excitation force is studied.In this paper,the cross stiffness of impeller clearance is calculated and analyzed.By means of hydrodynamics,the fluid force calculated and deduced.Meanwhile ANSYS is also used to calculate and analyze the pressure distribution of the impeller under different loads.Thirdly,the SAMCEF/Rotor software is used to establish the rotor system model.By analyzing the modal and critical speed of rotor subsystem,the relationship between the critical speed and the support stiffness and damping is obtained.The relation between the unbalance mass and the critical speed is obtained by analyzing the unbalance response of the rotor.The relationship between the critical speed and the stiffness and damping of the support is obtained by analyzing the transient response of the rotor.The relationship between rotor system instability and rotational speed is obtained by analyzing the rotor unbalance response supported by sliding bearing.Finally,the proportional model is used to predict the impact vibration of the rotor-bearing system,and the response calculation and analysis of the rotor system under different impacts of the rotor are carried out.For the calculation of the rotor with reduced proportional size,it is of great guiding significance to design and calculate the rotors with different sizes.
Keywords/Search Tags:Centrifugal compressor, Sliding bearing, Fluid excitation, Reduced scale size
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